This invention pertains to the Marine Sciences, and, more specifically, to the field of electro-oceanography. More explicitly, the invention pertains to the transfer of electrical power from a rapidly moving surface source into the sea. By way of further description of the field encompassed thereby, the invention pertains to an electrode structure useful for the transfer of electrical power into the sea water for producing magnetic disturbances therein. The electrode structure is particularly adapted for direct current applications.
In modern times, the oceanographic and naval sciences have placed increased reliance on aircraft as research vehicles. Specifially, the oceanographic maping and minesweeping arts have increasingly made use of the high-powered, heavy-lift, rotary wing type of aircraft as a tow vehicle for their respective apparatus. The use of the aircraft to perform the vehicular duties has permitted a much larger area to be covered for a given expenditure of time, manpower, and money. However, the high cost-per-unit of time of aircraft operation has placed greater demands on the reliability of the equipment deployed by the aircraft.
Although weakening and breakage of the prior art electrodes have seldom occurred as a result of their being towed by slow-moving ships, boats, and the like, breakages thereof have been frequent and troublesome when towed by fast-moving aircraft. Hence, as a result of such fast towing, the electrodes of the prior art have had to be repaired quite often, something which is especially difficult and dangerous to do during military maneuvers. Moreover, such problems seem to be compounded when using the more modern direct current type of field generating electrodes of the prior art.
The development of suitable electrode structures for the aircraft towed oceanographic instrumentation has lagged behind the other components of the system. In the majority of instances, reliance is placed on electrode structure designed and configured to be streamed from much slower surface vessels. These units have proven to be unsatisfactory in many instances. The electrodes designed for surface towing have excessive bulk and weight for optimum deployment in aerial towed applications. Furthermore, and perhaps most importantly, the drag load imposed by these large and cumbersome devices have prevented their acceptance for use in aerial towed application.
Aerially towed electrodes of the prior art were simply lengths of uninsulated metallic copper cable. In addition to their heavy weight, such electrodes have a drag load nearly as great as their surface towed counterparts. Furthermore, the life expectancy of these prior art electrodes was short and unpredictable. The short life is due to a high rate of electrolytical erosion weakening the individual wire strands.
Prior art constructions have avoided the use of lightweight metals, since it is commonly supposed that the oxide products which are formed in static applications would coat the electrode, thereby electrically insulating it from the water and destroying its effectiveness.
Attempts to overcome these prior art deficiencies have resulted in buoyant coverings being placed over the copper cable electrodes. These prior art coverings were designed to permit the water to come into contact with the cable electrode and were satisfactory for alternating current applications. However, these coverings impaired the electrical efficiency especially for direct current applications by trapping ions and thereby creating a polarization voltage opposing the electrode voltage. Further, the thermal insulating properties of the covering cause the electrode to become heated by the current flow therein, further impairing its electrical performance. Also, the coverings prevented ready inspection of the electrode by maintenance personnel between operational deployments.
The aforementioned problems have posed continual application problems in the aerially conducted electro-oceanographic operations. This invention incorporates an electrode and electrode system which overcome these prior art difficulties.